Java 5 fails with "zip file closed". See nabble link.

I assume it's because versions 287 & 288 are being signed by an expired certificate

sm 330420 Tue Mar 03 16:59:54 EST 2009 winstone.jar

X.509, EMAILADDRESS=kk@kohsuke.org, CN=Thawte Freemail Member
[certificate expired on 2/23/09 11:02 AM]

The workaround is to either go to earlier versions which weren't signed when the
certificate had expired or move to Java 6.